Oxides of copper and aluminum are used as catalyst precursors in the manufacture of butynediol-1,4 or other organic compounds. U.S. Pat. No. 4,009,124 teaches a method to make a basic mixed carbonate of copper and aluminum with a defined crystal structure, which, after annealing at 350° to 600° C., produces an amorphous phase, particularly active as a catalyst. The process involves milling and sifting of the annealed product to obtain a suitable particle distribution e.g. from 60 to 200 μm. Discrete forms suitable for use as fixed-bed catalysts are also used.
Novel processes for the manufacture of titanium dioxide from aqueous solutions have been disclosed in PCT Publications WO 01/00530, WO 01/00531, and WO 01/12555, the relevant portions of which are incorporated herein by reference. In general, these applications describe the processing of an aqueous solution of a titanium salt by evaporation to produce an intermediate. The evaporation is conducted at a temperature higher than the boiling point of the solution, but lower than the temperature where significant crystal growth of an oxide phase occurs. In some embodiments, the evaporation may be conducted at a temperature higher than the boiling point of the solution but lower than the calcination temperature of the intermediate.
In the case of titanium solutions, the temperature generally ranges from 120° to 350° C., and preferably from 200° to 250° C. The process is preferably conducted by spraying, and can be accomplished in a spray dryer. The spray drying process produces thin-filmed spheres or parts of spheres, with a diameter of about 1 to 100 μm, and a shell thickness of about 0.03 to 5 μm.
After calcination and milling of these spheres or parts of spheres, and depending on the conditions of evaporation, the choice of additives and the conditions of calcination, ultra-fine nano-sized TiO2 or, alternatively, pigment grade TiO2 can be obtained.
There has been no suggestion, however, that such a process can economically and commercially produce mixed metal oxides and metal oxide compounds. The present invention is therefore directed to a process to economically produce intimate mixtures of oxides or compounds formed from a mixture of oxides, starting from aqueous solutions of salts of different metals.